The new technology of integrated optics is expected in coming years to provide new devices for communications and signal processing, especially in conjunction with fiber optic transmission systems. Integrated optics is an attractive approach to these devices because there is the potential for very high performance operation using optical processing principles, in structures that can be very small and rigid, and manufactured by batch fabrication techniques.
One of the components required for integrated optic signal processing devices is an efficient modulator, capable of manipulating the intensity or position of the light beam at very high frequencies. There are many methods of modulating light in optical waveguides, including electro-optic, magneto-optic, and acousto-optic with acousto-optic surface waves. An advantage of a waveguide modulator based upon acousto-optic interactions is that there is a greater number of available film materials that can be used, while electro-optic or magneto-optic modulators have relatively few. Furthermore, many good acousto-optical films can be deposited upon a choice of substrates, in amorphous form. This makes possible the fabrication of hybrid integrated optic circuits, in which each component may be chosen to be made of a material which will optimize its function.
One known thin film wave guide material is As.sub.2 S.sub.3. This material has a high acousto-optical figure of merit (i.e., it is very efficient in modulating or deflecting light with sound), but it does not transmit light in the very useful wavelength of 0.6328 microns, produced by the helium-neon laser.